Such a device is in fact known for example from document EP1923034A1, which discloses a spring system accommodated in a support block. This spring system is formed of two symmetrical flaps preferably made of a flexible polymer material and each formed of an upper wing and a lower wing articulated to one another and when at rest forming an obtuse angle. These flaps are also positioned back-to-back at their articulation and the upper wings are configured to form an accommodating space for the object. The lower wings are connected to one another by a torsion spring that cooperates with a pushbutton arranged to move perpendicular to a pressure sensor until coming into contact therewith or releasing itself therefrom.
The introduction of an object into the accommodating space, for example a vial of an injectable pharmaceutical solution, causes the upper wings, the first ends of which are fixed because they are connected to the support block by means of lugs and slots, to move apart. Since the first ends are fixed, the moving apart of the upper wings causes a moving apart in a horizontal direction of their movable second ends which, by means of the articulation, is transmitted to each of the two flap wings, these second flap wings being connected at two free ends of the torsion spring by hooks on each of the movable ends of the second wings, so that the moving apart of these two movable ends is converted by means of the tension of the torsion spring into a vertical force acting on the pushbutton. The pushbutton then moves in the direction of the pressure sensor until it comes into contact therewith when the torsion spring is in its pushed position, which causes the emission of a first electrical impulse translating this movement of introduction and, consequently, the presence of this object in the accommodating space, said first impulse being processed by a processing means arranged to convert this first impulse into a signal indicating the presence of the object in the accommodating space.
By contrast, the removal of an object from its accommodating space causes the upper wings to move towards one another in a horizontal direction, due to the release of the tension of the spring that is in a rest position (i.e. in a position where the torsion spring is in a rest state and therefore undergoes no torsion tension) and simultaneously that of the contact of the pushbutton with the pressure sensor. This pushbutton then moves away from this sensor causing the emission of a second electrical impulse indicating that this movement has occurred and, consequently, that this object is absent from the accommodating space, said second impulse being processed by the processing means arranged to convert this second impulse into a signal indicating the absence of the object in the accommodating space.
These electrical impulses, which constitute data concerning the movement of these objects, can be transmitted, depending on requirements, via an electronic card and for example a Wi-Fi network, for example to a computer processing unit for their use by the appropriate software.
The vertical movement of the pushbutton is guided by the presence of longitudinal raised portions that cooperate with the slots present on a tubular portion in which the pushbutton is housed.
Unfortunately, such a method has one major drawback due to the fact that, on the one hand, the dimensions of the torsion spring must be adapted to suit the dimensions of the object to be detected, which results in an additional set-up cost of the accommodating system and, on the other, it has been observed that the operation of the torsion spring, which consists in the transmission of the horizontal movement of the wings away from or towards one another in a vertical movement of the pushbutton, seriously deteriorates over time, to such an extent that this spring must frequently be replaced.
The weakening of the spring is all the more significant as the upper and lower wings of each flap become stiff with use. In fact, the stiffness of the wings stresses the spring more intensely to the extent that, on placing the object in the accommodating space, a first thrust force of the object generated by the contact of the object with each wing of each flap is directly transferred to the torsion spring which, over time, becomes weaker. A direct consequence of this weakening is that, on removing the object from its accommodating space, the torsion spring struggles to regain its rest state and the rise of the pushbutton is slowed down or even ineffective, which poses a particular problem when the device is used for applications that require a monitoring of movement in real time.
Typically, the increased stiffness of the flaps is caused, for example, by oxidation over time of the originally flexible polymer material that constituted each wing, or by the fact that the device is intended to house vials containing a drug that must be kept in a cold chamber, said device therefore needing to be placed repeatedly, at least during loading, in this cold chamber.
Moreover, the use of a torsion spring makes the assembly of the accommodating system laborious as the person skilled in the art must ensure that the spring remains attached to each hook on each of the movable ends of the second wings when inserting the system in the housing and fitting the lugs present on each flap into the recesses provided in the housing.
Furthermore, it was found that, whenever a person skilled in the art used the state-of-the-art device and wanted to insert or remove the object from the accommodating space, if the object is rotated about an axis parallel to the direction of insertion or removal, the torsion spring can come out of its position and become unhooked from the wings, which means that the device must be used precisely and carefully.